Xgard ASU
Xgard Air Sampling Unit (ASU)
Installation, Operation and Maintenance Instructions
M07646
Issue 9
September 2016
Introduction
The Air Sampling Unit (ASU) is designed to be used with Crowcon’s Xgard range of
detectors for monitoring potentially hazardous gases within ventilation ducts. The ASU
operates using the Venturi principle, for which the air flow rate within the duct must be
between 5 metres per second and 20 metres per second.
Installation
The Xgard gas detector must be fitted to the ASU prior to assembly onto the duct. A full
assembly drawing is shown on the next page. The ASU is not compatible with the Xgard
Type 4 high temperature gas detector.
1. To avoid the adverse effects of turbulence, the ASU should be installed in the centre
of a straight section of duct which has a length of at least six times its width.
2. Check the air flow direction in the air duct system.
3. Apply the drilling template onto the centre line of the air duct parallel to the air flow.
Check that the directional arrow on the drilling template is the same as the direction
of the air flow in the duct.
4. Using a centre punch, punch the two centres indicated for the drilling template.
5. Drill out to 25mm (1”) diameter. Remove burrs and sharp edges around the two
holes.
6. Remove the ASU cover.
7. Fit the sample tube elbows with rubber washers on the inside and outside of the
sampling chamber. Fit the securing nuts and tighten. Ensure that the black sample
tube holes face 180º away from the sample chamber, and the white sample tube
chamfer faces away from the sample chamber as shown on the diagram on the next
page.
8. Check the thickness of the air duct metalwork and fit the black rubber grommets into
the two duct holes drilled for point 5 of these instructions.
9. Fit the ASU probes through the two grommets checking that the inlet and outlet
probes are correctly installed and push until the unit has sealed.
10. Mark the six ASU plate fixing holes and drill 5mm (1/4”) holes for securing the plate.
Secure the plate to the duct using suitable bolts.
11. Connect the detector cable as instructed in the Xgard manual.
12. Check that there is no air leakage into the sampling chamber from outside the
duct through the probe joints, grommets or sampling unit cover gasket.
Testing and Commissioning
Calibrate the detector according to its instructions. Testing the operation of the ASU can be
performed by introducing gas into the duct system.
Warning: it is essential to ensure that procedures are in place to prevent people and/or
equipment being affected by any test gas introduced into the ventilation system.
Operation and maintenance
The ASU needs no specific maintenance however the Xgard gas detector must be
maintained in accordance with its instructions.
Specifications
Xgard ASU Part Number: S011843
Suitable Duct Widths: 300mm (12”) to 1500mm (60”)
Suitable Air Speeds: 5 metres (3’3”) to 20 metres (13’) per second
Operating Temperature Range: 0ºC (32ºF) to +60ºC (140ºF)
Drilling Template Label Dimensions
© Crowcon Detection Instruments Ltd 2016
UK Office
Crowcon Detection Instruments Ltd
172 Brook Drive,
Milton Park,
Abingdon
Oxfordshire OX14 4SD
Tel: +44 (0)1235 557700
Fax :+44 (0)1235 557749
Email: [email protected]
Website: www.crowcon.com
USA Office
Crowcon Detection
Instruments Ltd
1455 Jamike Ave, Suite 100
Erlanger
Kentucky 41018
Tel: +1 859 957 1039 or
1 800 527 6926
Fax: +1 859 957 1044
Email: [email protected]
Website: www.crowcon.com
European Office
Crowcon Detection Instruments Ltd
Vlambloem 129
3068JG
Rotterdam
Netherlands
Tel: +31 10 421 1232
Fax: +31 10 421 0542
Email: [email protected]
Website: www.crowcon.com
Singapore Office
Crowcon Detection
Instruments Ltd
Block 194 Pandan Loop
~06-20 Pantech Industrial Complex
Singapore 128383
Tel: +65 6745 2936
Fax: +65 6745 0467
Email: [email protected]
Website: www.crowcon.com
China Office
Crowcon Detection Instruments Ltd
(Beijing)
Unit 316, Area 1, Tower B, Chuangxin
Building
12 Hongda North Road, Beijing Economic
Technological Development Area
Beijing, China 100176
Tel: +86 10 6787 0335
Fax: +86 10 6787 4879
Email: [email protected]
Website: www.crowcon.com
Crowcon reserves the right to change the design or specification of this product without notice.
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